1. Field of the Invention
The present invention relates to a disc changer, and in particular, to improvement of a disc housing portion, a disc conveyance mechanism and a playback portion and a reproducing method of an information recording medium in the disc changer.
2. Description of the Related Art
Heretofore in the past, the disc changer which houses and reproduces various kinds of disc type information recording medium (hereinafter, referred to simply as “disc”) such as CD (Compact Disc), DVD (Digital Versatile Disc) and the like has been put to practical use. This disc changer comprises a housing portion for housing a plurality of discs, a conveyance mechanism for conveying the housed disc to the playback portion and a playback portion for reproducing the disc conveyed to the playback portion.
As for the disc housing portion as described above, in recent years, as shown in FIG. 1, there has been known a disc housing portion, wherein a disc-shaped rotary type housing portion (hereinafter, referred to as “rotary stocker”) 100 is provided, where a housing groove (hereinafter, referred to as “slot”) 101 for housing one piece of the disk in an upstanding state is provided radially in plural pieces, and one disc is selected from among all the discs housed in the rotary stocker and is reproduced. Note that, in FIG. 1, reference numeral 200 denotes a conveyance mechanism of the disc, and reference numeral 300 or 500 denotes a playback portion.
Examples of the prior arts of the housing portion, the conveyance mechanism and the playback portion in the disc changer comprising such a rotary stocker have been as follows.
First, in the disc housing portion, when the disc housed in the slot 101 of the rotary stocker 100 as shown in FIG. 1 is to be taken out, the number of the slot (hereinafter, referred to as “designated takeout slot”) in which a desired disc is housed was inputted by a numeric keypad and the like, and a microcomputer (not shown) controlled a stocker-driving portion based on this input signal so as to rotate the rotary stocker 100, and moved the designated takeout slot nearly to a center (disc exchange position)of a disc inserting and takeout opening portion 10.
Next, though the conveyance mechanism of the disc is a mechanism for conveying the selected disc to a predetermined place, in the case of the disc changer having a function for reproducing both sides, the disc is transferred from a disc housing position to a transfer position opposed 180 degrees across a long stroke.
For example, Japanese Patent Application Laid-Open No. 11-219559 discloses a structure for transferring the disc by an arm rotatably provided. This, as shown in FIG. 13A, constitutes an arm 401 in which a plurality of members are rotatably linked around a horizontal axis, and a base end portion 403 of a lower part arm 402 is rotatably provided on the upper surface of a base 404, thereby constituting a conveyance mechanism 400.
As shown in FIG. 13A, when the arm 401 is rotated, the outer periphery of a disc D is held by an engaging portion 405 of the arm 401, and this disc D is taken out from the housing position on the holder 406, while being laterally rotated. When the arm 401 is further rotated, as shown in FIG. 13B, the disc D held by the arm 401 is transferred to a playback portion 407, which is located nearly in the center portion of a holder 406. By further rotating this arm 401, the disc is transferred from the housing position of the holder 406 to the transfer position not shown, which is opposed 180 degrees.
The prior art in the playback portion of the disc is as follows. That is, in said rotary stocker, each disc is housed in an upstanding state, and the disc selected by the conveyance mechanism is conveyed to the playback portion in a nearly vertical state. The disc conveyed to the playback portion has been reproduced in the playback portion in a nearly vertical state.
In the above-described disc changer, there existed the following problems in each prior art of the disc housing portion, the conveyance mechanism and the playback portion.
That is, as shown in FIG. 1, the disc exchange opening portion 10 in the disc housing portion has a width to simultaneously expose plural pieces of discs by taking into consideration easiness of disc exchange. Accordingly, from this opening portion 10, not only the disc housed in the designated takeout slot, but also the disc housed in the slot in the vicinity of the designated takeout slot are exposed together. As a result, at the first glance, it was difficult to judge which is the disc housed in the designated takeout slot, thereby causing a trouble in taking out the disc.
Further, in the case where the disc is housed in a slot adjacent to the designated takeout slot, this disc housed in the adjacent slot acted as a hindrance and made it very difficult to take out the disc from the designated takeout slot.
On the other hand, when the disc is housed in the desired slot, the slot in which the disc is desired to be housed was moved nearly to a center (disc exchange position) of the opening portion 10 by the above-described procedure. In this case also, since not only the designated housing slot, but also the slot in the vicinity of the designated housing slot are exposed together from the opening portion 10, at the first sight, it was very difficult to judge which is the designated housing slot. As a result, it was necessary to go through a troublesome procedure wherein, after the number of the designated housing slot is visually confirmed, the disc is housed.
Hence, a first object of the present invention is to facilitate a takeout operation of the disc from the desired slot and a housing operation of the disc into the desired slot in the disc changer so that operability is exceptionally enhanced.
Next, the disc conveyance mechanism 400 described relative to FIG. 13A and FIG. 13B has involved the following problem. That is, the base 404 provided in a base end portion of the arm 401 requires a space for a lower part arm 401, which advances upward from the upper surface of the base 404. For this reason, a stroke to transfer the disc D becomes longer by that much. Further, the arm 401 is provided in such a manner as to cover the disc D from the upper surface of the base 404 to the upper part. For this reason, in order to transfer the disc D, the arm 401 rotates on a large scale on the base 404 with the base end portion 402 as a center, so that a large space is required for this purpose. Owing to these reasons, downsizing of the mechanism has been difficult to attempt.
Hence, a second object of the present invention is to attempt a steady transfer of the disc and downsizing of the mechanism in the disc conveyance mechanism of the disc changer.
Further, since the play back portion in the disc changer reproduces the disc in a nearly vertical state, an object lens and the like of a pick-up in the playback portion are applied with a load by a dead weight, and a motor shaft which rotates the disc is applied with a load by the dead weight of the disc and the motor shaft so as to reduce rotational accuracy, thereby causing a problem that the disc cannot be reproduced in a steady state.
Hence, a third object of the present invention is to provide a disc changer capable of reproducing the disc in a steady state and a reproducing method of information recording medium.